In present wireless communication systems, such as a GSM communication system, base stations transmit a Calling Identity Delivery (CID) message to mobile devices in the coverage cells via paging messages. Where no incoming call is placed, the base station nevertheless periodically transmits a dummy paging message without substantial content (i.e., the CID message), so that synchronization between the base station and the mobile device can be maintained. In practice, the base station transmits dummy paging messages most of the time.
FIG. 1 is a partial schematic function block diagram of a transmitting end/receiving end in a communication system. The transmitting end 10 may be a transmitting device of the base station, and the receiving end may be a receiving device of the mobile communication device. In a GSM communication system, the original message codes of the substantial paging message and the dummy paging message include 228 bit data, where 40 bits of the 228 bits are redundancy codes for error detection at the receiving end 20. After a ½ code rate convolution coding procedure provided by the encoder 12, the original message codes are transformed into 456-bit coded data. The interleaver 14 is responsible for dispersing the coded data into four bursts, each of which includes 114 bits data. Then, the four bursts may be processed by the mapping unit 16 and the modulating unit 18 to be transmitted in the form of a RF signal in sequence.
The RF receiver 21 of the receiving end 20 may receive the RF signals corresponding to the four bursts in sequence. After demodulation by the demodulator unit 22, elimination by the impulse response procedure of the channel equalizer 23, rearrangement by the deinterleaver 24 and decoding by the decoder 25, these RF signals are converted back into 228 bits of restored message code. Then, the subsequent circuit is responsible for determining whether the restored message code represents a substantial paging message or a dummy paging message and perform appropriate subsequent processing accordingly.
Theoretically, the receiving end 20 only determines the type of the paging message after it has received all four bursts and rearranges them to form the restoring message code. However, if the paging message is a dummy paging message, all four bursts do not contain substantial messages, such as calling information. As a result, it is not power-efficient to receive many dummy messages for the mobile devices.
In the present field of art, there have been developments of technologies that determine whether the paging message is a substantial paging message only according to a first burst of the four bursts. When it is determined that the paging message is a dummy paging message according to the determination result, the receiver of the communication apparatus stops receiving the signals related to the follow three bursts, thereby reducing the power consumption. However, in a situation of serious noise interference, misjudgment may occur when determination of whether the paging message is a substantial paging message is made only according to the first burst. As a result, substantial paging messages including important information may be lost.